Blind-stitch sewing machine



Aug. 15, 1944. v M. ,BUoNo I BLIND- STITCH SEWING MACHINE Filed June 17, 1940 Patented Aug. 15, 1944 Mario Buono, Brooklyn, N. Y.,

assignor to U. S.

Blind Stitch Machine Corporation, New York, N. Y., a corporation of New York Application June 17, 1940, Serial No. 340,944

5 Claims.

My invention relates to improvements in a sewing machine, and more particularly, a blindstitch sewing machine.

One of the objects of the invention is to provide improved means for forming the bight in the work.

Another object of the invention is to provide a blind-stitch sewing machine in which the height of the bight-forming member is Aautomatically adjusted in accordance with the thickness of the work. Another object of the invention is to provide improved means for sewing work which is of diiferent thickness along a line which is either parallel to or perpendicular to the line of feed. Another object of the invention is to provide a bight-forming member which has a projection which abuts the lower side of a part of the work during the formation of the blind stitch, s that the height of the bight which is formed in the work is automatically regulated according to the thickness of the material.

Otherobjects of the invention will be set forth in the following description and drawing which illustrate a certain preferred embodiment, it being understood that the above statement of the objects of my invention is intended to generally explain the same Without limiting it in any man- Fig. 1 is a front elevation, partially in section, of a sewing machine to which the improvements have been applied.

Fig. 2 is a sectional View on the line 42--2 of Fig. l.

Fig. 3 is a sectional view on the line 3-3 of Fig. 2.

Fig. 4 is a sectional View on the line 4 of Fig. 3. Fig. 4 is made exactly according to scale and it represents a full-sized device which is made according to one embodiment of the invention, although the invention is not limited to the details of Fig. 4.

Fig. 5 is a perspective view showing one of the types of work which is done by the improved machine. V

The blind-stitch sewing machine can be of any standard type. The invention is shown as applied to that type of blind-stitch sewing machine in which the bight in the work is formed by means of an oscillating member. The machine has the usual head H, and the well-known needle arm I, which is oscillated by any suitable mechanism. The curved needle 2 is of the usual type. The rock shaft 4 which is mounted in suitable bearings 1 and 8, is also conventional. The

rock shaft 4 is oscillated by any suitable mechanism which operates the well-known link 5, which is pivotally connected to the rock-shaft 4 in the usual manner. This rock-shaft is located in the frame C.

The work isy held down on the work-supporting member, by the well-known resilient plate 9 while the stitch is formed in the bight of the work. The above parts are found in numerous types of standard blind-stitch sewing machines which are well known in the trade.

The improved support I0 has a body which has a recess I9, in orderrtoprovide the spaced legs Il and I2. The bight-forming member I3 is turnably located between said legs II and I2. The threaded shank of a pivot screw IG extends through respective bores of said legs II and I2, which are aligned with the bore I3b of the bightforming member I3. There is a slight clearance between the edge-Wall of said bore I3bl and the shank of the pivot screw I6. A nut I5 holds the screw I6, assembled with the support I0.

One end of biasing tension spring I'I is connected to the wall of the bore I3c of the bightforming member I3. The other end of biasing tension spring I'I is connected to lug Ia, which is integral with support I.

The support I0 has a hub through which shaft 4extends. Said hub of support Ill is xed in any suitable manner to rock shaft 4, so that said support I8 oscillates in unison with rock shaft 4.

Fig. 4 is drawn according to full scale, in order clearly to illustrate one embodiment of the invention, although the invention is not limited to the shapes or to the other details of Fig. 4.

At one face thereof, the bight-f'orming member is provided with a lateral pin I4.

In the stitch-forming position which is shown in Fig. 2, the planar top-wall of pin I4 is substantially horizontal.

- Said bight-forming member I3 has a top convex wall. As shown in Fig. 2, when the stitch is formed, the bight is formed by the anterior portion of said convex wall. Said anterior portion is therefore Vdesignated as the bight-forming edge-wall. The forked shoe 9 can depress said bight-forming edge-wall from its normal position, by means of the pressure of the work, in proportion to the thickness of the work, at the time that the respective blind-stitch is formed.

In-the normal position of said bight-forming member IS, a corner of'its inner end-Wall abuts' a corner of the inner end-wall of recess' I9, thus providing stop-means to limit the movement of1 support.

the bight-forming member I3 relativeto I under the biasing force of spring I l. However, the bight-forming member can turn clockwise around pivot-screw I6, from the normal position.

When said stop-means are effective, the bightforming edge-wall is located a maximum distance above the rock-shaft 4, and closest to the path in which the needle is oscillated.

When the respective blind-stitch is formed, the chord of the convex bight-forming edge-wall is downwardly inclined, as shown in Figs. 2 and 4.

'Ihe leg I2 is of less width than leg Il, thus providing ample clearance between leg I2 and pin I4.

The length or lateral dimension of the pin I4, along a line which is perpendicular to the free planar end-face of said pin, is shown on a greatly exaggerated scale in Fig. 3. In the bightforming member which is shown in full scale in Fig. 4, the lateral dimension of said nger I4 is about of an inch.

lln the normal position of the bight-forming member i3, relative to the support I0, which is shown in 4, the vertical distance between the central axis of the shaft 4 and the horizontal planar surface of the finger I4, is 0.572 of an inch. The horizontal distance between the median line of the planar surface of the member I4 and the aXis of the shaft 4, is 0.103 of an inch. In Fig. 4 the line A passes through the center ofthe bore I 3b and the axis of the shaft 4. The line B is parallel to the line A and said line B passes through the edge of the planar surface of the member i4 which is nearest to the axis of the bore E31). The distance between the lines A and B is approximately 0.500 of an inch.

In operating the sewing machine, the shaft 4 is turned clockwise, until the planar surface of the finger I4 is moved to a position in which said planar surface is horizontal or substantially horizontal. The finger I4 is maintained in said position. The needle then passes the; thread through the bight of the work while finger I4 is in said position. This bight is formed by and itA is supported on, the chamfered surface I3d of the rib member I3. Said chamfered surface has a sharp or narrow edge. When the stitch is formed in the bight of the work, the median line of the planar surface of the member I4, which is perpendicular' to the line of feed of the work, is substantially directly underneath the point at which the needle passes thro-ugh the bight of the work or material. rIhis is illustrated in Fig. 2, which shows the position of the support I and of its bight-forming member I3, when the stitch is formed in the bight of the work. The rock-shaft 4 and the support I0 are held stationary during the very short interval of time which is required for passing the thread of the needle 2 through the bight of the work. The period during which the support Ill is thus maintained stationary, is only a very small part of the total period of oscillation of the curved needle 2. The shaft 4 is turned clockwise, thus forming the bight in the work, whilerthe needle 2 is being moved towards the bight. The support I0 is maintained stationary while the point and the eye of the needle are being passed through the bight of the work. As soon as, or shortly after, the Veye of the needle has been passed through the bight of the work, the shaft 4 can be turned counter-clockwise, so as to move the member I3 downwardly relative to the work. The work is then supported by the conventional supporting means, which are not shown. When the formation of the bight in the work has been completed and before the point of the needle enters the bight of the work, the horizontal surface of the member I4 abuts the underside of the work, and the upper surface of the work abuts the undersides of the Xed legs of the shoe 9 or of some other abutment member 3 which is located above the bight of the work. 'I'he clearance between the planar top surface of the finger I4 and the underside of the xed abutment member, is dimensioned in accordance with the general class of work which is to be done by the machine, so that the finger I4 is depressed by the work below the normal position of said finger I4, and this depression of the finger I4 depends upon the thickness of the work at one side of the bight. The chamfered surface I3a of the bight-forming member i3 forms the bight, so that the height of the top of the bight, and its vertical relation to the path of the needle, is regulated wholly by the automatic adjustment of the member i3 relative to the support I0. The bight is not formed under any circumstances by the top surfaces of the members I I and I2.

Fig. 5 shows a lining L which is sewed in folded condition to base material M, which may consist of one or more layers of material. As shown in Fig. 3, when the machine operates on this class of work, the needle is first passed through the lining L at the folded edge thereof, and the needle then forms a blind stitch in the layer or layers of material M. Likewise, the split shoe 9 may then hold the work downwardly as illustrated in Fig. 3 directly at each side of the member I3, so that the needle passes through the top part of the bight, which is located in the slot of shoe 9. The formation of the bight and the formation of the stitch is therefore determined by the thickness of the work at one side of the member I3, in doing the class of work which is shown in Fig. 5. The machine will therefore function properly when the work differs in thickness along a longitudinal line whichis parallel to the line of feed. Likewise the work may vary in thickness along a line which is transverse to the line of feed, as for example, where the work has a crossseam which is located at each side of the member I3. The thickness of the work therefore dee termines the vertical distance between the path of the needle and the apex of the bight of the work. While a finger I4 could be provided at each side of the member I3, it is preferred to have only one linger I4, which projects laterally from one face of the member l 3.

As shown in Fig. 2, when the bight-forming member is moved against the force of the biasing spring, the portion of the bight-forming member which is then directly underneath the needle, is moved downwardly relative to the path of the needle. Hence the bight-forming member has an effective up-and-down movement relative to the path of the needle, said bight-forming mem-Y ber being moved downwardly against the force of the biasing spring, and being moved upwardly by the biasing spring.

The means which hold the legs of the bight down, such as the legs of the shoe il or the like, may be either rigid or resilient.

The machine may be designed so that the finger i4 will be depressed when the thickness of the work above said finger exceeds 164th ofA an inch. A machine which is thus designed',

can handle work whose thickness above the finger is as great as T35 of an inch. The free downward movement of finger i4, relative to the rock shaft 4, is great enough to permit this vartition in thickness of the work. Fig. 3 shows that when the nger I4 is depressed during the formation of the stitch, the bottom of the work rests partially on the leg I2, which is adjacent the finger I4. The other side of the work may or may not abut the outer edge of the leg II. As shown in Fig. 2, the leg I2 is narrower than leg II, in order to permit the downward movement of finger I4. The relative dimensions which are shown accurately in Fig. 4 are important in securing proper operation.

Numerous other changes and omissions can be made from the preferred embodiment which is illustrated herein, without departing from the spirit of the invention.

I claim:

1. In a blind-stitch sewing machine, the combination of a rock-shaft, a support connected to said rock-shaft and movable in unison with said rock-shaft, a bight-forming member pivotally connected to said support, said bight-forming member having a lateral work-engaging nger which is located below the top of the said bightforming member, spring means connected to said support and to said bight-forming member and biasing the bight-forming member to a position in which its top is located above the top of the support, said bight-forming member being.

the sole means for forming the bight in the work.

2. In a blind-stitch sewing machine, the combination of a rock-shaft, a support connected to said rock-shaft and movable in unison with said rock-shaft, a bight-forming member pivotally connected to said support, said bight-forming member having a lateral work-engaging nger which is located below the top of the said bight-forming member, said work-engaging nger having a substantially planar top surface, spring means connected to said support and to said bight-forming member and biasingr the bight-forming member to a position in which its top is located above the top of the support, said bight-forming member being the sole means for forming the bight in the work.

3. A blind-stitch sewing machine comprising a needle, means adapted to move the needle back-and-forth in a predetermined path, a rockshaft located underneath said path of the needle, a support connected to said rock-shaft and movable in unison with said rock-shaft, a bightforming member pivotally connected to said support, said bight-forming member having a lateral nger, said nger having a planar surface, the rock-shaft being adapted to hold said planar surface substantially horizontal and with the lateral median line of said planar surface substantially directly underneath the path of the needle during the period in which the needle passes the thread through the bight, spring means connected to said support and to said bight-forming member and biasing the bightforming member to a position in which its top is located above the top of the support, said bightforming member being the sole means for forming the bight in the work.

4. For use in a blind-stitch sewing machine, a support having separated legs, a bight-forming member located between said legs and pivotally connected to said legs, spring means adapted to hold the bight-forming member yieldingly in a predetermined position relative to said support, said bight-forming member having a lateral positioning finger which projects laterally beyond one of said legs, said finger being spaced from the adjacent edge of said leg when the bightorming member is in said predetermined position, the top of the bight-forming member being located above the top of the support when the bight-forming member is in said predetermined position, said bight-forming member being the sole means to form a bight in work to be blind-stitched.

5. A blind-stitch sewing machine having a needle and means adapted to move said needle back-and-forth in a predetermined path, a bight-forming member, a support to which said bight-forming member is movably connected, said support and said bight-forming member being located below said path, said support being movable up-and-down relative to said path, said said bight-forming member being thus moved up-and-down in unison with said support, said bight-forming member having a lateral finger connected thereto, said lateral iinger being located to abut the adjacent portion of the underside of the work to be blind-stitched when the needle is penetrating said work, said machine also having means which are located above said finger and which are adapted to abut the top of said Work above said finger, spring means yieldingly biasing said bight-forming member to a position in which the top of said bight-forming member is located above the top of said support, said bight-forming member being the sole means for forming the bight in the work to be blindstitched.

MARIO BUONO. 

